It is well known in the prior art to produce air cell cushioning product on a rotating forming drum utilizing flexible thermoplastic sheet material by embossing one of the sheets on the drum and then applying a laminating or cover sheet thereto for sealing formation of the air cells, with such air cell product being utilized for instance in cushioning applications. See for instance U.S. Pat. Nos. 3,142,599; 3,285,793 and 3,416,984. Such prior art methods and apparatus usually comprise heating not only the film to be embossed to a high temperature either substantially at or above the fusion temperature of the film material, but also heating the laminating film to a temperature at about the fusion temperature prior to application of the laminating sheet to the heated embossed sheet. Such prior art arrangements are not only relatively energy inefficient, resulting in increased production costs, but also involve more expensive arrangements for the apparatus and the controls therefor, resulting in greater relative overall costs.
In applicant's copending U.S. patent application Ser. No. 75,662, filed Sept. 14, 1979 and entitled "Cushioning Dunnage Product, Apparatus and Method" there is disclosed a method and an apparatus for producing air cell cushioning dunnage which includes a cooling step for cooling the product on the rotating forming drum to a particular temperature prior to application of the laminating sheet to the embossed sheet on the drum, and which results in an air cell product having some of the same general characteristics as those of the product with the present apparatus and method. In certain other respects however, the produced products are different.
Moreover, there are considerable other prior art patents in the air cell cushioning dunnage field, such as for instance U.S. Pat. Nos. 3,018,015; 3,231,454; 3,349,990; 3,577,305 3,586,565; 3,389,534; 3,523,055; 3,575,781; 3,616,155; 3,785,899; 3,817,803; 3,837,990; 3,837,991; 3,868,056; 4,076,872; 4,096,306; and 3,771,388, and the Australian Pat. No. 160,551. The above are merely representative, and it is not meant to imply that such a list is all inclusive.
These prior art methods and apparatus are not generally of the type which can be readily and conveniently interrupted in operation and then restarted, without having considerable undesirable effects upon the resultant product, or on the film stock material utilized to produce the product, and/or on the mechanism or apparatus per se. Moreover, such prior art mechanisms if they do possess the ability to be interrupted in operation, are generally of a rather complex, non-compact nature, and which generally utilize considerable energy in the formation of their respective thermoplastic air cell products.